Lymphoblastoid cell lines and burkitt‐lymphoma‐derivee cell lines differ in the expression of a second epstein‐barr virus encoded nuclear antigen

192

105

SUMMARYAll Epstein-Barr virus (EBV) isolates can be classified as type A or type B depending upon the identity of their EBV nuclear antigen (EBNA) 2 protein. The great majority of isolates examined to date encode an EBNA 2A protein like that of the reference type A strain B95-8. Type B virus strains, encoding an antigenically distinct EBNA 2B protein, have as yet only been rescued from rare Burkitt's lymphoma (BL) cell lines of African origin (Jijoye, AG876). Our recent finding that type B isolates are less efficient than type A in in vitro transformation assays prompted us to determine (i) the relative contribution the two types of virus make to the incidence of BL in endemic areas of Africa (Kenya) and New Guinea and (ii) the relative incidence of infection with these two types in the normal population in these same areas. On the first point, EBNA 2 gene typing using specific DNA probes showed that four of ten recently established Kenyan BL cell lines and two of four BL cell lines from New Guinea carried type B virus isolates. To address the second point, spontaneous lymphoblastoid cell lines were established from the blood of normal virus carriers and typed for EBNA 2 at the protein level; a significant proportion (> 20 ~) of the normal population in both the above BLendemic areas were infected with type B isolates. This is the first indication of the widespread nature of type B virus infection in any community and the first isolation of such viruses from a non-BL source. The reproducible size of the EBNA 2B protein encoded by all type B isolates irrespective of their geographical origin, and of the EBNA 1 protein encoded by all type B isolates from one area, contrasted markedly with the extreme variability in the size both of EBNA 2A and of EBNA 1 seen generally among type A isolates. This suggests that the number of type B virus strains in existence worldwide could be quite limited. Most importantly, the data suggest that type B viruses, despite their relatively poor performance in in vitro transformation assays, can contribute at least as efficiently as can type A viruses to the pathogenesis of BL.

Section: Discussionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 99%

New Type B Isolates of Epstein--Barr Virus from Burkitt's Lymphoma and from Normal Individuals in Endemic Areas

Young

Yao

Rooney

et al. 1987

192

105

“…Immunoblotting was performed as previously described (Ernberg et al, 1986;Gratama et al, 1988;Rowe & Gregory, 1989). The following primary antibodies were used.…”

Section: Methodsmentioning

confidence: 99%

“…In families one predominant variant was found. Within a small geographical area, however, unrelated individuals show a wide distribution of variants (Ernberg et al, 1986;Gratama et al, 1990;Yao et al, 1991). In contrast, the coexistence of multiple Ebnotypes was frequently detected in recipients of allogenic bone marrow or organ transplantation (Gratama et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

The role of repetitive DNA sequences in the size variation of Epstein--Barr virus (EBV) nuclear antigens, and the identification of different EBV isolates using RFLP and PCR analysis

Falk

Gratama²,

Rowe

et al. 1995

The six Epstein-Barr virus (EBV) nuclear antigen proteins show characteristic size variations between different virus isolates; this is a feature that has been used to identify the source of virus isolates in epidemiological studies (Ebnotyping). We have now studied the correlation between restriction fragment length polymorphisms (RFLPs) within exons coding for the EBNAs and the molecular masses of the respective proteins. The B95-8 EBV strain was used as the prototype virus. The variation in apparent molecular mass of EBNA-1, -3 and -6 correlated positively with the size of RFLP coding for repeat sequences in these polypeptides. For EBNA-2, no correlation between apparent molecular mass and length of the repetitive sequences was found. The EBNA-4 protein showed virtually no variation in apparent molecular mass and RFLP size across the repeat sequence. Based on the strong correlation between apparent molecular mass and RFLP size for EBNA-6, we developed an EBNA-6 PCR assay that discriminated between different isolates of EBV. This assay offers the advantage of EBV characterization using uncultured material (e.g. throat washings, blood or biopsies), thus avoiding the selection against poorly transforming strains that occurs during establishment of lymphoblastoid cell lines required for Ebnotyping at the protein level.

“…The most significant changes are a reduction in the efficiency of transformation, making the establishment of B-type EBV cell lines difficult, and altered phenotypes in the emerging transformed cells (Rowe et al, 1989). The geographical distribution of these two virus types may also be different with the B-type virus having been identified in individuals living in endemic malarial regions of Africa and New Guinea (Ernberg et al, 1986;Zimber et al, 1986;Young et at., 1987;Sculley et al, 1988;Rowe et al, 1989). The present study was undertaken to determine the frequency of B-type EBV in BL from New Guinea and to ascertain whether EBV strains (both A-type and B-type) in New Guinea are different from those found in Africa.…”

Section: Introductionmentioning

confidence: 99%

Heterogeneity within the Epstein-Barr virus nuclear antigen 2 gene in different strains of Epstein-Barr virus

Sengupta

Aedes

Moss

et al. 1994